Chameleon skin. Do you know how?

Does anyone know how a Chameleon physiologically changes the color of its skin? I'm guessing the mechanism has to do with proteins in their epidermis that contain chromophores which can be controlled to vary their skin pigment. If anyone knows the details, please show me the devil.

Hi,
Although I cannot adequately address the physiological properties of chameleon skin, I would like to inform you of additional information on animal visual communication. The cuttlefish (a type of squid) seems to be studied more in its physiology, so its dazzling displays should be known to a better degree.
Google search (example): "cuttlefish and visual communication"ADAPTIVE COLORATION / CAMOUFLAGE link